The invention relates to an actuating mechanism for axial setting purposes, comprising three discs which are supported co-axially relative to an axis and of which a central disc is rotatable relative to the two outer discs. Between the central disc and each of the outer discs, there are arranged sets of balls. The balls each run in pairs of circumferential grooves in the faces of the central disc and of one of the outer discs facing one another. The circumferential grooves comprise a circumferentially variable depth.
Furthermore, the invention relates to an intermediate axle drive for vehicles driven by several axles.
Actuating mechanisms of the foregoing type are known from DE 39 28 816 C2 and DE 40 07 506 C1 and from DE 41 06 503 C1 wherein the two outer discs are provided for alternately opening and closing two friction couplings in a manual gearbox whose gear-wheels can be coupled in a force-locking way to an associated shaft by means of the friction couplings.
From the publication xe2x80x9cIntegrated Transfer Casexe2x80x9d by K. Lippitsch, submitted at the conference xe2x80x9cTagung Allradtechnikxe2x80x9d (Conference Four-wheel Technology) taking place from Feb. 10, 11, 2000 in xe2x80x9cHaus der Technik e.V.xe2x80x9d, there is known an intermediate axle drive concerning a two-stage gearbox and a central differential with one locking coupling. The locking coupling is actuated by a ball ramp mechanism with two co-axially supported discs, whereas the two stage drive is switched by a switching claw which can be actuated via an electromagnetic axial setting device.
It is an object of the invention to provide a setting mechanism of the initially named type which can be used for setting processes of different kinds, such as in intermediate axle drives.
The present invention provides an actuating mechanism of the foregoing type wherein, over the entire relative angle of rotation, the first outer disc moves axially from a first end position via a central position into a second end position which deviates from the first end position, and the second outer disc moves axially from a first end position via a second end position deviating therefrom back into the first end position.
Furthermore, the present invention provides an intermediate axle drive for a vehicle driven by several axles, comprising a two-stage gearbox and a follow-up central differential with a locking coupling. The intermediate axle gearbox comprises an actuating mechanism for axial setting purposes comprising three discs which are supported co-axially relative to an axis and of which a central disc is rotatable relative to the two outer discs. Between the central disc and each of the outer discs, there are arranged sets of balls, the balls each run in pairs of circumferential grooves iii the faces of the central disc and of one of the outer discs facing one another. The circumferential grooves comprise a circumferentially variable depth whose extension is such that, over of the entire relative angle of rotation, the first outer disc moves axially from a first end position via a central position into a second end position which deviates from the first end position. The second outer disc moves axially from a first end position via a second end position deviating therefrom back into the first end position. The first outer disc is connected by means of a shift fork to a gearshift sleeve for the two-stage gearbox and the second outer disc acts on a pressure plate of the locking coupling of the central differential.
In this way, it is possible to provide a device which, by means of standard rotary driving means, can achieve two different setting functions.
The central disc can be driven by a rotary drive and the outer discs can be held in a rotationally fast way in a housing, or the central disc can be held in a rotationally fast way in a housing and the outer discs can be driven synchronously by the rotary drive. Finally, by making use of a stage which reverses the direction of rotation, it is not impossible for the central disc and the outer discs to be driven simultaneously in opposite directions of rotation by the rotary drive.
With regard to a preferred use as an actuating mechanism for a two-stage gearbox and a locking coupling in an intermediate axle differential, the first outer disc, for example, over a first range of the angle of rotation, holds, without changing, its first end position; and over a second range of the angle of rotation, is axially transferred into the second end position; and, over a third range of the angle of rotation, holds, without changing, the second end position. The second outer disc, over the first range of the angle of rotation, changes from its first end position into the second end position; over the second range of the angle of rotation, holds, without changing, the second end position; and, over the third range of the angle of rotation, axially changes back from the second end position into the first end position.
In this way, the available relative range of rotation is divided into three. Thus, in a central range of rotation, the locking coupling of the differential drive is opened, with the two-stage gearbox being shifted from the first stage into the second stage, whereas in the two end ranges of the range of rotation, the gear stage as shifted is retained, and the locking coupling of the central differential is going to be progressively closed.
The central range for shifting between the two gear stages is divided up in such a way that within the axial shifting movement, there is additionally provided a central range in which a neutral position between the two gear stages is retained, without being changed, over a certain range of the angle of rotation of the discs. The respective position as set or the coupling condition can be recorded by a sensor at the central disc or at an element of the rotary drive of the disc.
The differential drive can, for example, be a planetary drive whose input shaft carries the web with the planetary gears, whose sun gear is connected to a first output shaft and whose hollow gear is positioned on a hollow shaft which rotates with the first output shaft and which, via an intermediate gear, drives a second output shaft. The locking device can be a multi-plate clutch which is effective between the web and hollow gear and which can be loaded via a pressure plate and an axial bearing by the second disc.
Other advantages and features of the invention will also become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.